Packaged microelectronic devices and methods for assembling microelectronic devices

ABSTRACT

Packaged microelectronic devices and methods for assembling microelectronic devices are disclosed herein. In one embodiment, a method of assembling a microelectronic device having a die and an interposer substrate includes depositing a solder ball onto a ball-pad on the interposer substrate and molding a compound to form a casing around at least a portion of the die and the solder ball. The method can further include forming a first cover over a first surface of the interposer substrate with the compound and forming a second cover over a second surface opposite the first surface of the interposer substrate with the compound. The first cover can have a first volume and a first surface area and the second cover can have a second volume and a second surface area. The first and second volumes and the first and second surface areas can be at least approximately equal.

TECHNICAL FIELD

[0001] The present invention is related to packaged microelectronicdevices and methods for assembling microelectronic devices.

BACKGROUND

[0002] Microelectronic devices generally have a die (i.e., a chip) thatincludes integrated circuitry having a high density of very smallcomponents. In a typical process, a large number of dies aremanufactured on a single wafer using many different processes that maybe repeated at various stages (e.g., implanting, doping,photolithography, chemical vapor deposition, plasma vapor deposition,plating, planarizing, etching, etc.). The dies typically include anarray of very small bond-pads electrically coupled to the integratedcircuitry. The bond-pads are the external electrical contacts on the diethrough which the supply voltage, signals, etc., are transmitted to andfrom the integrated circuitry. The dies are then separated from oneanother (i.e., singulated) by dicing the wafer and backgrinding theindividual dies. After the dies have been singulated, they are typically“packaged” to couple the bond-pads to a larger array of electricalterminals that can be more easily coupled to the various power supplylines, signal lines and ground lines.

[0003] An individual die can be packaged by electrically coupling thebond-pads on the die to arrays of pins, ball-pads, or other types ofelectrical terminals, and then encapsulating the die to protect it fromenvironmental factors (e.g., moisture, particulates, static electricityand physical impact). In one application, the bond-pads are electricallyconnected to contacts on an interposer substrate that has an array ofball-pads. FIG. 1 schematically illustrates a packaged microelectronicdevice 10 including an interposer substrate 20 and a microelectronic die40 attached to the interposer substrate 20. The microelectronic die 40has been encapsulated with a casing 70 to protect the die 40 fromenvironmental factors.

[0004] One drawback of encapsulating the microelectronic die 40 is thebowing or warpage of the interposer substrate 20 that occurs after thecasing 70 cools. The bowing is caused by the difference between thecoefficients of thermal expansion of the interposer substrate 20, themicroelectronic die 40, and the casing 70. The warpage of the interposersubstrate 20 can create sufficient stress to cause failure in the solderlinks between the interposer substrate 20 and a printed circuit board towhich the interposer substrate 20 is attached. Accordingly, there is aneed to reduce and/or eliminate the warpage in the microelectronicdevice 10.

[0005] Moreover, electronic products require packaged microelectronicdevices to have an extremely high density of components in a verylimited space. For example, the space available for memory devices,processors, displays and other microelectronic components is quitelimited in cell phones, PDAs, portable computers and many otherproducts. As such, there is a strong drive to reduce the height of thepackaged microelectronic device 10 and the surface area or “footprint”of the microelectronic device 10 on a printed circuit board. Reducingthe size of the microelectronic device 10 is difficult because highperformance microelectronic devices 10 generally have more bond-pads,which result in larger ball-grid arrays and thus larger footprints. Onetechnique used to increase the density of microelectronic devices 10within a given footprint is to stack one microelectronic device 10 ontop of another.

[0006]FIG. 2 schematically illustrates the packaged microelectronicdevice (identified as 10 a) of FIG. 1 stacked on top of a second similarmicroelectronic device 10 b. The interposer substrate 20 of the firstmicroelectronic device 10 a is coupled to the interposer substrate 20 ofthe second microelectronic device 10 b by large solder balls 80. Thelarge solder balls 80 required to span the distance between the twointerposer substrates 20 use valuable space on the interposer substrates20, and thus increase the footprint of the microelectronic devices 10.Accordingly, there is a need to reduce the footprints of stackedmicroelectronic devices 10.

SUMMARY

[0007] The present invention is directed to packaged microelectronicdevices and methods for assembling microelectronic devices. One aspectof the invention is directed to a method of packaging a microelectronicdevice including a die having an integrated circuit and an interposersubstrate having a ball-pad electrically coupled to the integratedcircuit. In one embodiment, the method includes depositing a solder ballonto the ball-pad and molding a compound to form a casing around atleast a portion of the die and at least a portion of the solder ball. Ina further aspect of this embodiment, the method can further includeforming a first cover over a first surface of the interposer substratewith the compound and forming a second cover over a second surfaceopposite the first surface of the interposer substrate with thecompound. The first cover can have a first volume and the second covercan have a second volume at least approximately equal to the firstvolume. In another aspect of this embodiment, the first cover can have afirst surface area and the second cover can have a second surface areaat least approximately equal to the first surface area.

[0008] In another embodiment of the invention, the method includesplacing the solder ball onto the ball-pad and encapsulating the die andthe first and second surfaces of the interposer substrate to form thefirst cover over the first surface and the second cover over the secondsurface. In a further aspect of this embodiment, the first cover canhave a first surface area and the second cover can have a second surfacearea at least approximately equal to the first surface area. In anotheraspect of this embodiment, the first cover can have a first volume andthe second cover can have a second volume at least approximately equalto the first volume. In further aspect of this embodiment, placing thesolder ball occurs before encapsulating the die and the first and secondsurfaces.

[0009] In another embodiment of the invention, a packagedmicroelectronic device includes a microelectronic die having anintegrated circuit and a bond-pad coupled to the integrated circuit andan interposer substrate coupled to the die. The interposer substrate hasa first surface, a second surface opposite the first surface, and aball-pad electrically coupled to the bond-pad on the die. Themicroelectronic device also includes a solder ball on the ball-pad and acasing covering the die, at least a portion of the first surface, and atleast a portion of the second surface. In a further aspect of thisembodiment, the casing can cover at least a portion of the solder ball.In another aspect of this embodiment, the casing includes a first coverand a second cover. The first cover has a first surface area and a firstvolume, and the second cover has a second surface area and a secondvolume. The first surface area can be at least approximately equal tothe second surface area, and the first volume can be at leastapproximately equal to the second volume.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a schematic cross-sectional view of a packagedmicroelectronic device including an interposer substrate and amicroelectronic die in accordance with the prior art.

[0011]FIG. 2 is a schematic cross-sectional view of the packagedmicroelectronic device of FIG. 1 stacked on top of a second similarmicroelectronic device in accordance with the prior art.

[0012]FIG. 3 is a top cutaway isometric view of a microelectronic devicethat is to be encapsulated using a method in accordance with oneembodiment of the invention.

[0013]FIG. 4 is a schematic cross-sectional view of a microelectronicdevice having an interposer substrate and a microelectronic die inaccordance with an embodiment of the invention.

[0014]FIG. 5 is a schematic cross-sectional view of the packagedmicroelectronic device of FIG. 4 stacked on top of a second similarmicroelectronic device in accordance with yet another embodiment of theinvention.

[0015]FIG. 6 is a schematic cross-sectional view of a microelectronicdevice in accordance with still another embodiment of the invention.

[0016]FIG. 7 is a schematic cross-sectional view of the packagedmicroelectronic device of FIG. 6 stacked on top of a second similarmicroelectronic device in accordance with yet another embodiment of theinvention.

[0017]FIG. 8 is a schematic cross-sectional view of a microelectronicdevice in accordance with still another embodiment of the invention.

DETAILED DESCRIPTION

[0018] The following description is directed toward packagedmicroelectronic devices and methods for manufacturing packagedmicroelectronic devices. Many specific details of several embodimentsare described below with reference to packaged microelectronic deviceshaving microelectronic dies and interposer substrates to provide athorough understanding of such embodiments. The present invention,however, can be practiced using other types of microelectronic devicesand/or micromechanical devices. Those of ordinary skill in the art willthus understand that the invention may have additional embodiments, orthat the invention may be practiced without several of the detailsdescribed in this section.

[0019] A. Environment

[0020]FIG. 3 is a top cutaway isometric view of a microelectronic device110 that is to be encapsulated using a method in accordance with oneembodiment of the invention. The microelectronic device 110 includes aninterposer substrate 120 and a microelectronic die 140 attached to theinterposer substrate 120 by an adhesive 160. The microelectronic device110 shown in FIG. 3 illustrates the interposer substrate 120 and themicroelectronic die 140 before encapsulating the die 140 with a moldcompound.

[0021] In the illustrated embodiment, the interposer substrate 120 has afirst surface 123, a second surface 124 opposite the first surface 123,and an elongated slot 125 between the first and second surfaces 123 and124 that extends lengthwise along a medial portion of the interposersubstrate 120. The interposer substrate 120 is generally an interposingdevice that provides an array of ball-pads for coupling very smallcontacts on the microelectronic die 140 to another type of device. Inthe embodiment shown in FIG. 3, the interposer substrate 120 includes afirst array of ball-pads 127, a second array of terminal pads 128proximate to the slot 125, and a trace 129 or other type of conductiveline between each ball-pad 127 and a corresponding terminal pad 128. Theinterposer substrate 120 can be a flexible material or a substantiallyrigid material, and the traces 129 can be conductive lines that areprinted on the substrate 120 in a manner similar to printed circuitboards.

[0022] The embodiment of the microelectronic die 140 shown in FIG. 3includes a first side 141 attached to the second surface 124 of theinterposer substrate 120 by the adhesive 160. The microelectronic die140 also includes a plurality of small bond-pads 142 and an integratedcircuit 144 (shown schematically) coupled to the bond-pads 142. Thebond-pads 142 are arranged in an array along the first side 141 of themicroelectronic die 140 so that the bond-pads 142 are aligned with orotherwise accessible through the slot 125 in the interposer substrate120. A plurality of wire-bonds or other types of connectors 150 couplethe bond-pads 142 of the die 140 to corresponding terminal pads 128 onthe interposer substrate 120. As such, the interposer substrate 120distributes the very small bond-pads 142 to the larger array ofball-pads 127.

[0023] B. Packaged Microelectronic Devices

[0024]FIG. 4 is a schematic cross-sectional view of a microelectronicdevice 210 having an interposer substrate 220 and a microelectronic die240 coupled to the interposer substrate 220 in accordance with oneembodiment of the invention. The interposer substrate 220 and themicroelectronic die 240 can be similar to the interposer substrate 120and microelectronic die 140 discussed above with reference to FIG. 3.The interposer substrate 220, for example, includes a first surface 223,a second surface 224 opposite the first surface 223, a first end 221,and a second end 222 opposite the first end 221. The microelectronic die240 includes a first end 241 and a second end 242 opposite the first end241. The microelectronic die 240 can also include bond-pads 246 that areelectrically coupled to first ball-pads 247 on the first surface 223 ofthe interposer substrate 220 and/or second ball-pads 249 (shown inbroken lines) on the second surface 224 of the interposer substrate 220.In other embodiments, the interposer substrate 220 may have only thefirst ball-pads 247, and the bond-pads 246 are thus coupled to only thefirst ball-pads 247 in such other embodiments.

[0025] The microelectronic device 210 of the illustrated embodiment alsoincludes a casing 270 encapsulating the microelectronic die 240, thefirst surface 223 of the interposer substrate 220, and the secondsurface 224 of the interposer substrate 220. The casing 270 can includea first cover 272 a over the first surface 223 of the interposersubstrate 220 and a second cover 272 b over the microelectronic die 240and the second surface 224 of the interposer substrate 220. The firstcover 272 a and the second cover 272 b can have at least approximatelythe same volume. Furthermore, the first cover 272 a can cover a firstsurface area on the first surface 223 and the second cover 272 b cancover a second surface area on the second surface 224 that is at leastapproximately equal to the first surface area. The first and secondcovers 272 a and 272 b can extend on each side of the interposersubstrate 220 from at least proximate to the first end 221 to at leastproximate to the second end 222. In other embodiments, the casing 270may not cover the entire first and second surfaces 223 and 224 of theinterposer substrate 220.

[0026] The microelectronic device 210 of the illustrated embodiment alsoincludes first encased solder balls 280 attached to first ball-pads 247proximate to the first surface 223 of the interposer substrate 220. Thefirst encased solder balls 280 and the first ball-pads 247 arepositioned either between the first end 241 of the microelectronic die240 and the first end 221 of the interposer substrate 220 or the secondend 242 of the microelectronic die 240 and the second end 222 of theinterposer substrate 220 in the illustrated embodiment. Themicroelectronic device 210 can also include second encased solder balls284 (shown in broken lines) attached to second ball-pads 249 (shown inbroken lines) proximate to the second surface 224 of the interposersubstrate 220. Each second encased solder ball 284 is attached to theinterposer substrate 220 approximately opposite a corresponding firstencased solder ball 280 in the embodiment of FIG. 4 such that the firstand second encased solder balls 280 and 284 are positioned approximatelythe same distance from the first and second ends 221 and 222 of theinterposer substrate 220. In other embodiments, however, the first andsecond encased solder balls 280 and 284 may not be opposite each other.In the illustrated embodiment, the first encased solder balls 280 areelectrically coupled to the microelectronic die 240. In anotherembodiment, the second encased solder balls 284 can be electricallycoupled to the die 240, and/or the first and second encased solder balls280 and 284 can be electrically coupled to each other with pass-throughcircuitry.

[0027] In the illustrated embodiment, the first encased solder balls 280project beyond the first cover 272 a by a distance D₁. In otherembodiments, such as the embodiments described below with reference toFIGS. 6 and 7, the first encased solder balls 280 may not project beyondthe first cover 272 a. In additional embodiments, the microelectronicdevice 210 may not include second encased solder balls 284, or it mayinclude second encased solder balls 284 that project beyond the secondcover 272 b. In still other embodiments, the microelectronic device 210can include additional ball-pads and solder balls across the firstand/or second surfaces 223 and 224 of the interposer substrate 220, suchas described below with reference to FIG. 8.

[0028] The microelectronic device 210 of the illustrated embodiment, canbe manufactured by attaching at least one set of the first and secondencased solder balls 280 and 284 to the interposer substrate 220. Next,the interposer substrate 220, the microelectronic die 240, and at leastportions of the first and second encased solder balls 280 and 284 areencapsulated. In one embodiment, the interposer substrate 220, themicroelectronic die 240, and the first and second encased solder balls280 and 284 are positioned in a mold for encapsulation. The mold caninclude a liner, such as a non-stick tape or non-stick film. The firstencased solder balls 280 are pressed partially into the liner as themold clamps to the interposer substrate 220. The liner prevents themolding compound from covering the entire first encased solder balls280. Accordingly, the portion of the first encased solder balls 280 thatis pressed into the liner is the portion that projects beyond the firstcover 272 a. Once the interposer substrate 220, the microelectronic die240, and the first and second encased solder balls 280 and 284 arepositioned in the mold, a molding compound is injected into the mold andformed around the interposer substrate 220, the microelectronic die 240,and the first and second encased solder balls 280 and 284. In otherembodiments, the interposer substrate 220, the microelectronic die 240,and the first and second encased solder balls 280 and 284 can beencapsulated using other methods.

[0029] One advantage of the embodiment illustrated in FIG. 4 is that theapproximately equal volumes and/or surface areas of the first and secondcovers 272 a and 272 b eliminate the warping and bowing of themicroelectronic device 210. The stresses that cause warping can occurwhen the microelectronic device 210 cools after encapsulation. Thestresses occur because the interposer substrate 220, the microelectronicdie 240, and the first and second covers 272 a and 272 b have differentcoefficients of thermal expansion. The thermal stresses do not causewarping in the embodiment illustrated in FIG. 4 because the stress onone side of the microelectronic device 210 offsets the stress on theother side due to the approximately equal volumes and/or surface areasof the first and second covers 272 a and 272 b.

[0030]FIG. 5 is a schematic cross-sectional view of the microelectronicdevice (identified as 210 a) of FIG. 4 stacked on top of a secondsimilar microelectronic device 210 b in accordance with anotherembodiment of the invention. The first microelectronic device 210 a iscoupled to the second microelectronic device 210 b by attaching thefirst encased solder balls 280 of the first microelectronic device 210 ato a generally flat surface 285 on the second encased solder balls 284of the second microelectronic device 210 b. In one embodiment, thegenerally flat surface 285 can be formed by grinding the second encasedsolder balls 284. In another embodiment, the generally flat surface 285can be formed by the mold during encapsulation. In this embodiment, themold may not contain the liner discussed above with reference to FIG. 4,or the liner may not be compressible. Accordingly, the mold flattens aportion of the second encased solder balls 284 forming the flat surface285. In the illustrated embodiment, the first microelectronic device 210a is spaced apart from the second microelectronic device 210 b by thedistance D₁. In other embodiments, the microelectronic devices 210 canbe coupled to other devices, such as printed circuit boards.

[0031] One advantage of the embodiment illustrated in FIG. 5 is that thesize of the encased solder balls 280 and 284 used to couple the firstand second microelectronic devices 210 a and 210 b can be reduced. Byusing two solder balls rather than one solder ball to span the distancebetween the microelectronic devices, each solder ball can have a smallerdiameter. Solder balls with smaller diameters use less space on theinterposer substrate. Consequently, the size of the interposer substratecan be reduced, thereby decreasing the footprint of the interposersubstrate on a printed circuit board.

[0032]FIG. 6 is a schematic cross-sectional view of a microelectronicdevice 310 in accordance with another embodiment of the invention. Themicroelectronic device 310 can include the interposer substrate 220, themicroelectronic die 240, the casing 270, and the second encased solderballs 284 (shown in broken lines) described above. The microelectronicdevice 310 also includes first encased solder balls 380 attached to thefirst ball-pads 247 proximate to the first surface 223 of the interposersubstrate 220. Each first encased solder ball 380 can have a generallyflat surface 381 opposite the interposer substrate 220. In oneembodiment, the flat surface 381 of the first encased solder balls 380can be formed by grinding the first encased solder balls 280 describedabove with reference to FIG. 4. In additional embodiments, the generallyflat surface 381 can be formed in the molding process as discussed abovewith reference to FIG. 5. The microelectronic device 310 furtherincludes exterior solder balls 386 attached to the generally flatsurface 381 of the first encased solder balls 380.

[0033]FIG. 7 is a schematic cross-sectional view of the microelectronicdevice (identified as 310 a) of FIG. 6 stacked on top of a secondsimilar microelectronic device 310 b in accordance with anotherembodiment of the invention. The first microelectronic device 310 a canbe coupled to the second microelectronic device 310 b by attaching theexterior solder balls 386 to the second encased solder balls 284.Accordingly, the size of the exterior solder balls 386 determines thedistance D₂ between the first and second microelectronic devices 310 aand 310 b.

[0034]FIG. 8 is a schematic cross-sectional view of a microelectronicdevice 410 in accordance with another embodiment of the invention. Themicroelectronic device 410 of the illustrated embodiment includes theinterposer substrate 220, the microelectronic die 240, and the casing270 described above. The microelectronic device 410 also includes firstencased solder balls 480 attached to the first ball-pads 247 proximateto the first surface 223 of the interposer substrate 220. The firstencased solder balls 480 can be arranged between the first end 241 andthe second end 242 of the microelectronic die 240. In the illustratedembodiment, each of the first encased solder balls 480 has a flatsurface 481 opposite the first surface 223 of the interposer substrate220. The flat surface 481 can be formed by grounding and/or molding asdiscussed above with reference to FIG. 6. After the microelectronicdevice 410 is encapsulated with the casing 270, exterior solder balls486 can be attached to the first encased solder balls 480. Accordingly,each exterior solder ball 486 is attached to the flat surface 481 of acorresponding first encased solder ball 480. In other embodiments, themicroelectronic device 410 may not include the exterior solder balls486. In additional embodiments, the microelectronic device 410 caninclude additional ball-pads and solder balls to permit coupling and/orstacking, such as described above with reference to FIGS. 4-7.

[0035] From the foregoing it will be appreciated that the embodiments ofthe invention described above provide the best mode of the invention andprovide sufficient disclosure to enable a person skilled in the art tomake and use these embodiments, but that modifications may be made tothese embodiments that add or delete features without deviating from thespirit and scope of the invention. Therefore, the scope of the inventionis not limited except as defined only by the claims that follow.

1-48. (Canceled)
 49. A packaged microelectronic device, comprising: amicroelectronic die having an integrated circuit and a bond-pad coupledto the integrated circuit; a dielectric interposer substrate coupled tothe die, the dielectric interposer substrate having a first surface, asecond surface opposite the first surface, and a ball-pad electricallycoupled to the bond-pad on the die; a solder ball on the ball-pad; and acasing covering the die, at least a portion of the first surface, and atleast a portion of the second surface, wherein the casing includes afirst cover at least proximate to the first surface and a second coverat least proximate to the second surface, and wherein the first coverhas a first volume and the second cover has a second volume at leastapproximately equal to the first volume.
 50. The microelectronic deviceof claim 49 wherein the ball-pad is a first ball-pad at least proximateto the first surface, wherein the solder ball is a first solder ball,wherein the interposer substrate further comprises a second ball-pad atleast proximate to the second surface, and wherein the microelectronicdevice further comprises a second solder ball on the second ball-pad.51. The microelectronic device of claim 49 wherein the solder ball isfirst solder ball, and wherein the microelectronic device furthercomprises an exterior solder ball on the first solder ball.
 52. Themicroelectronic device of claim 49 wherein the die has a first end and asecond end opposite the first end, and wherein the solder ball ispositioned on the interposer substrate between the first end and thesecond end of the die.
 53. The microelectronic device of claim 49wherein the interposer substrate includes an end, and wherein the solderball is positioned on the interposer substrate between the end and thedie.
 54. The microelectronic device of claim 49 wherein the solder ballhas a first portion proximate to the interposer substrate and a secondportion opposite the first portion, and wherein the second portionincludes a generally flat surface.
 55. The microelectronic device ofclaim 49 wherein the solder ball projects beyond the casing.
 56. Themicroelectronic device of claim 49 wherein the solder ball is at leastpartially encased by the casing.
 57. The microelectronic device of claim49 wherein the first cover has a first surface area and the second coverhas a second surface area at least approximately equal to the firstsurface area.
 58. A packaged microelectronic device, comprising: amicroelectronic die having an integrated circuit and a bond-pad coupledto the integrated circuit; a dielectric interposer substrate coupled tothe die, the dielectric interposer substrate having a first surface, asecond surface opposite the first surface, and a ball-pad electricallycoupled to the bond-pad on the die; a solder ball on the ball-pad; and acasing covering the die, at least a portion of the first surface, and atleast a portion of the second surface, wherein the casing includes afirst cover at least proximate to the first surface and a second coverat least proximate to the second surface, and wherein the first coverhas a first surface area and the second cover has a second surface areaat least approximately equal to the first surface area.
 59. Themicroelectronic device of claim 58 wherein the solder ball is at leastpartially encased by the casing.
 60. The microelectronic device of claim58 wherein the first cover has a first volume and the second cover has asecond volume at least approximately equal to the first volume.
 61. Apackaged microelectronic device, comprising: a microelectronic diehaving an integrated circuit and a bond-pad coupled to the integratedcircuit; a dielectric interposer substrate coupled to the die, thedielectric interposer substrate having a first surface, a second surfaceopposite the first surface, and a ball-pad electrically coupled to thebond-pad on the die; a solder ball on the ball-pad; and a casingcovering the die, at least a portion of the first surface, at least aportion of the second surface, and at least a portion of the solderball, wherein the casing includes a first cover at least proximate tothe first surface and a second cover at least proximate to the secondsurface.
 62. The microelectronic device of claim 61 wherein the firstcover has a first volume and the second cover has a second volume atleast approximately equal to the first volume.
 63. The microelectronicdevice of claim 61 wherein the first cover has a first surface area andthe second cover has a second surface area at least approximately equalto the first surface area.
 64. A microelectronic device, comprising: amicroelectronic die having an integrated circuit and a bond-pad coupledto the integrated circuit; a dielectric interposer substrate coupled tothe die, the dielectric interposer substrate having a first surface, asecond surface opposite the first surface, a first ball-pad on the firstsurface, and a second ball-pad on the second surface, wherein at leastone of the first and second ball-pads is electrically coupled to thebond-pad on the die; a first solder ball on the first ball-pad; a secondsolder ball on the second ball-pad; and a casing covering the die, atleast a portion of the first surface, at least a portion of the secondsurface, and at least a portion of the first and second solder balls,wherein the casing includes a first cover at least proximate to thefirst surface and a second cover at least proximate to the secondsurface.
 65. The microelectronic device of claim 64, further comprisingan exterior solder ball on the first solder ball.
 66. Themicroelectronic device of claim 64 wherein the interposer substrateincludes an end, and wherein the first and second solder balls arearranged on the interposer substrate between the end and the die. 67.The microelectronic device of claim 64 wherein the first solder ballprojects beyond the casing.
 68. The microelectronic device of claim 64wherein the first cover has a first volume and the second cover has asecond volume at least approximately equal to the first volume.
 69. Themicroelectronic device of claim 64 wherein the first cover has a firstsurface area and the second cover has a second surface area at leastapproximately equal to the first surface area.
 70. A set ofmicroelectronic devices, comprising: a first microelectronic device,comprising: a die having an integrated circuit and a bond-pad coupled tothe integrated circuit; a dielectric interposer substrate coupled to thedie, the dielectric interposer substrate having a first surface, asecond surface opposite the first surface, a first ball-pad on the firstsurface, and a second ball-pad on the second surface, wherein at leastone of the first and second ball-pads is electrically coupled to thebond-pad on the die; a first solder ball on the first ball-pad; a secondsolder ball on the second ball-pad; and a casing covering the die, atleast a portion of the first surface, at least a portion of the secondsurface, and at least a portion of the first and second solder balls,wherein the casing includes a first cover at least proximate to thefirst surface and a second cover at least proximate to the secondsurface; and a second microelectronic device, comprising: a die havingan integrated circuit and a bond-pad coupled to the integrated circuit;a dielectric interposer substrate coupled to the die, the dielectricinterposer substrate having a first surface, a second surface oppositethe first surface, a first ball-pad on the first surface, and a secondball-pad on the second surface, wherein at least one of the first andsecond ball-pads is electrically coupled to the bond-pad on the die; afirst solder ball on the first ball-pad; a second solder ball on thesecond ball-pad, wherein the second solder ball is coupled to the firstsolder ball of the first microelectronic device; and a casing coveringthe die, at least a portion of the first surface, at least a portion ofthe second surface, and at least a portion of the first and secondsolder balls, wherein the casing includes a first cover at leastproximate to the first surface and a second cover at least proximate tothe second surface.
 71. The set of microelectronic devices of claim 70,further comprising an exterior solder ball attached to the first solderball of the first microelectronic device and the second solder ball ofthe second microelectronic device.
 72. The set of microelectronicdevices of claim 70 wherein the first solder ball of the firstmicroelectronic device is attached to the second solder ball of thesecond microelectronic device.
 73. The set of microelectronic devices ofclaim 70 wherein the first cover of the first microelectronic device hasa first volume and the second cover of the first microelectronic devicehas a second volume at least approximately equal to the first volume.74. The set of microelectronic devices of claim 70 wherein the firstcover of the first microelectronic device has a first surface area andthe second cover of the first microelectronic device has a secondsurface area at least approximately equal to the first surface area.